Refillable ferrule fuse



Oct. 4, 1932. D. E. CARNEY REFILLABLE FERRULE FUSE Filed July 23, 1950 Patented Oct. 4, 1932 UNITED STATE DANIEL E. GARNEY, 01F PITTSBURGH, i nnnsnrlvnnranssrsnon on ONE-THIRD re;

JAMES M. MAGEE AND ONE-THIRD 'ro nanny r. NEAMAN, or rrr'rsnuncn, rnnnsrn- VANIA.

EIEIEILLABLE FERR'ULE FUSE Application filed July 23, 1930, Serial No. 470,163, and in Canada September 18, 1929.

This invention relates to refillable fuses of the type known in-the electrical art as the ferrule fuse.

In prior art fuses of this type, well rep resented by the constructions embodied in United States Patents 861,965 of July 30,

1907 to Gehrke; 1,180,767 of April 25, 1916 to Eustice; and 1,436,919 of November 28, 1922 to Smith; much difiiculty has developed fromthe trapping effect of their internal structure, which localizes the molten metal resulting from blow-outs, at the ends of the fiber insulating shell. This results in a comparatively rapid burning away of the shell, materially shortening the life of the fuse casing, and requiring frequent replacement.

The present invention is designed to overcome and avoid the defects of prior art practice, and has in addition to such objects as will be apparent to those skilled in the art, other objects which include: the provision of a'refillable ferrule fuse having self-contained follower means for compensating deterioration of the fuse shell at the ends thereof; the provision in a fuse of this character,

of means prohibiting the localization of molten deposits at the ends of the insulating shell; and the provision in such a fuse, of a simplestructural assembly presenting a bore of uniform diameter from endto end thereof.

This specification and, accompanying drawing, describe and illustrate a practical embodiment of the invention, constituting the best means l have thus far devised for reducing the invention to practice.

Figure 1 is a central longitudinal section through a fuse constructed in accordance with the invention.

Figure 2 is a group perspective illustrating an end assembly, with end plugremoved.

Figure 3 is an end elevation of the fuse casing per se.

Figure 4 is a similar end elevation of an assembled fuse, with end plug removed.

A preferred fuse structure comprises a tubular shell ofinsulating material, preferably fiber composition, externally threaded at each end to receive tubular metal ferrules 11 threaded thereon and extending beyond each end of the shell, said shell and ferrules forming the fuse casing. The ferrules are permanently secured in fixed relation to the shell by-retaining elements, such as pins or rivets 12 passed transversely through the ferrule and shell.

Abutting each end of the shell is an 8X- tcrnally threaded annular follower member 13 having an axial thickness much greater than that of an ordinary contact disk or washer asconnnon to the art; 'lhese followers have each a bore whose diameter is coincident with the diameter of the shell bore, and they are threaded within the ferrules into tight sealing engagement against the shell ends by means of a. suitable tool, engageable in diametrically opposed notches or grooves 1 1 provided for the purpose in the outer end face of each follower and extending through the follower body.

Metal contact disks 15-1541 having an eccentric chordia'l closed end slot 16' formed therein, are seated over the open end of each follower 13, with said slots, 16, arranged in diagonally opposed relation, and loosely arranged through said slots, 16, is a conventional fuse strip element 17 having its outer ends 18 bent downward over the outer face of each contact disk and overlying the major area thereof. The contact disk 15 is, preferably, provided with threads for engagement with threads on its associated ferrule and bears against the outer end of the follower 13. The slot 16 may act as a socket to receive a tool for convenient manipulation of disk 15. The diameter of disk 150; is less than the minimum internal diameter of its associated ferrule 11 so that it is freely insertable and removable therefrom.

The fuse casing is closed at each end by an externally threaded metal plug 19 threaded into its associated ferrule to bear against the fuse strip portion 18 and contact disk 15, 15a, tightly clamping the fuse strip portion therebetween and forcingthe contact disk tightly against the adjacent follower 13. tool receiving socket 20 is provided in the outer face of each plug for convenient manipulationthereof.

It is characteristic of this general type of fuse that spattering of molten metal incident to a blow-out is localized at the ends, and particularly at the lower end when the fuse is vertically disposed on a panel, as in the majority of instances. In the constructions of prior art practice, a portion of the molten metal is trapped against the metal bafiie presented by the contact washer or disk at the end of the shell, and lies on the inner face of the shell, rapidly burning through.

In the present invention, no part of the follower 1.3 extends radially inwardof the fuse bore, thus eliminating a'bafile effect, and the axial thickness of the follower is such that a relatively large metal surface is presented in back of each disk 15. The molten metal thus collects on the inner face of the follower, eliminating a burning out of the fiber shell.

By reason of the equal diameter of the shell bore and follower bores, the inner faces of these respective members are flush at their meeting points, presenting no internal irf tion, the grooves 14 of the followers provide circuitous vents for the escape of gases around the edges of the disks 15 and outwardly along the threads of the end plugs and ferrules.

In cleaning the fuse it is necessary to remove only the end plugs and disks 15 and 15,

thus presenting an open bore of uniform diameter and unbroken surface from end to end of the casing.

It is to be understood that I do not wish to limit myself to using a screw threaded contact disk, as a contact disk shown at 15a may be used at both ends.

I claim:

1. In a ferrule fuse, the combination of a cylindrical insulating shell, a ferrule rigidly secured on an end thereof and extending therefrom, an annular follower threaded into said ferrule intight bearing engagement against the adjacent end of the shell and having a bore equal in diameter to the shell bore,

' a fusible element, a contact disk insertable in said ferrule to seat on the follower and slotted to receive part of the fusible element therethrough, and a closure plug threaded into said ferrule to clamp a portion of the fusible element between said plug and contact disk.

2. In a ferrule fuse, the combination of a cylindrical insulating shell having a bore of uniform diameter from end to end, an internally threaded metal ferrule rigidly secured on and extending beyond an end of the shell, an externally threaded annular metal follower adjustably threadablc into said ferrule in tight bearing engagement against the adjacent shell end, said followerhaving a smooth central bore equal in diameter to the diameter of the shell bore and said follower having a considerable axial thickness, a fusible element in the casing, a contact disk insertable in said ferrule to seat on said follower, said disk being slotted to receive a portion of the fusible element therethrough, and an externally threaded end plug detachably threaded into said ferrule to clamp a portion of said fusible element between the plug and contact disk and clamping said disk against said follower.

3. In a ferrule fuse, the combination of a cylindrical insulating shell, ferrules rigidly secured on each end thereof, annular followers threaded into said ferrules in tight bearing engagement against adjacent portionsof the shell and having each a bore equal in diameter to the shell bore, a fusible element, a contact disk insertable in each ferrule to abut the adjacent follower and being slotted to receive part of the fusible element therethrough, one of said contact disks being peripherally threaded for engagement with its associated ferrule, and a closure plug threaded into each ferrule to clamp a portion of the fusible element between each plug and adjacent contact disk.

4. In a ferrule fuse, a cylindrical shell of insulating material, a metal ferrule secured to an end thereof and extending tl'ierefrom, l

an annular metal follower threaded into said ferrule in tight bearing engagement througlr out its inner end with the adjacent casing end, a fusible element, a metal contact disk 7 insertable in said ferrule to seat over and upon the outer end of the follower and slotted to receive part of the fusible element therethrough, a closure plug having threaded engagement with the ferrule to clamp 1 a portion of the fusible element between the plug and disk, and said follower having ,a notch -in its outer end through the wall mysignature. 

